Abstract : In this paper, we focus on two challenges to enable human-robot collaboration in factories. The first challenge is to evaluate the acceptability of an operator to work with a robot on a new collaborative task. Comparing physical and virtual situation, we highlight notions related to acceptability which can be evaluated using virtual reality. This will able us to evaluate future collaborative scenarios before their setting-up on supply chains. The second challenge is to provide a natural collaboration between the robot and the operator. We chose to study gesture recognition to enable a smooth collaboration. With this method, the robot should be able to understand its environment, adapt its speed and be synchronized with the operator. We used two use cases to test our frameworks, to evaluate them and to highlight possible improvements.